 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.handlers;

 import java.util.Hashtable ;

 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExecutableExtension;
 import org.eclipse.jface.commands.ToggleState;

 /**
  * <p>
  * A toggle state that can be read from the registry. This stores a piece of
  * boolean state information.
  * </p>
  * <p>
  * When parsing from the registry, this state understands two parameters:
  * <code>default</code>, which is the default value for this item; and
  * <code>persisted</code>, which is whether the state should be persisted
  * between sessions. The <code>default</code> parameter defaults to
  * <code>false</code>, and the <code>persisted</code> parameter defaults to
  * <code>true</code>. If only one parameter is passed (i.e., using the class
  * name followed by a colon), then it is assumed to be the <code>default</code>
  * parameter.
  * </p>
  * <p>
  * Clients may instantiate this class, but must not extend.
  * </p>
  *
  * @since 3.2
  */
 public final class RegistryToggleState extends ToggleState implements
         IExecutableExtension {

     /**
      * Reads the <code>default</code> parameter from the given string. This
      * converts the string to a boolean, using <code>true</code> as the
      * default.
      *
      * @param defaultString
      * The string to parse; may be <code>null</code>.
      */
     private final void readDefault(final String defaultString) {
         if ("true".equalsIgnoreCase(defaultString)) { //$NON-NLS-1$
 setValue(Boolean.TRUE);
         }
     }

     /**
      * Reads the <code>persisted</code> parameter from the given string. This
      * converts the string to a boolean, using <code>true</code> as the
      * default.
      *
      * @param persistedString
      * The string to parse; may be <code>null</code>.
      */
     private final void readPersisted(final String persistedString) {
         if ("false".equalsIgnoreCase(persistedString)) { //$NON-NLS-1$
 setShouldPersist(false);
         }

         setShouldPersist(true);
     }

     public final void setInitializationData(
             final IConfigurationElement configurationElement,
             final String propertyName, final Object data) {
         if (data instanceof String ) {
             // This is the default value.
 readDefault((String ) data);
             setShouldPersist(true);

         } else if (data instanceof Hashtable ) {
             final Hashtable parameters = (Hashtable ) data;
             final Object defaultObject = parameters.get("default"); //$NON-NLS-1$
 if (defaultObject instanceof String ) {
                 readDefault((String ) defaultObject);
             }

             final Object persistedObject = parameters.get("persisted"); //$NON-NLS-1$
 if (persistedObject instanceof String ) {
                 readPersisted((String ) persistedObject);
             }

         } else {
             setShouldPersist(true);
             
         }
     }
 }

